"Behold I, Paul, say to you that if you receive circumcision, Christ will be of no benefit to you. And I testify again to every man who receives circumcision, that he is under obligation to keep the whole Law. You have been severed from Christ, you who are seeking to be justified by law; you have fallen from grace." (Galatians 5:2-4)Paul is not saying that if you, or your parents, had you circumcised then you are forever doomed to a live apart from the grace of God. Rather, he is writing to those who wanted part of the law and part of grace. They wanted to trust in some aspects of the law while still claiming to rely on the grace of God in the other areas of their lives. They are the "Christ Plus" crowd. Their message was that you need Jesus plus circumcision for salvation. There are many versions of the "Christ Plus" crowd even today, but whenever we add anything to Christ, it always ends up as law.
The Greek term Paul uses for "obligation" literally means to "own". When we purchase part of the law for ourselves (in this case, circumcision) then we purchase the entire law and are obligated to keep the entire law. The law cannot be appropriated piecemeal, it is an all-or-nothing proposition. Keeping one part of the law does you no good if you offend in other areas of the law. The law's benefits are only realized if you keep all the law.
The problem with the law is that it is incompatible with grace. The law knows nothing of grace and grace knows nothing of law. Just as you cannot serve two masters, you cannot serve law and live by grace at the same time. We must either live by the law or live by grace but we cannot live in a mixture of the two.
When we try to live in mixture, Paul tells us that we end up being severed from Christ and fallen from grace. The idea of the Greek term here translated as "severed" means to be separated to the point where we no longer benefit from the source. For example, a leaf that has been severed from the tree may still live a bit longer on its own but it no longer benefits from the strength and life that the tree provides. In time it will die because it has been severed from the source. When we try to live by the law, even just a part of the law, we separate ourselves from the benefits of Christ. Its not that Christ has become powerless but rather that we have removed ourselves from the source of that power. Furthermore, the Greek term for "fallen" can also be interpreted as being diverted from one's course or path. We may start out well, but if we revert to trusting in the law, then we are diverted in the path of our life from a path of grace to a path of bondage. Our choice to trust in the law diverts our lives and chooses for us an alternate path that does not lead to life and sanctification.
The decision is ours, we must choose. We must choose the course and nature of our lives. We must choose to trust in Jesus and His salvation or trust in Moses and the law that he brought. John said, "For the Law was given through Moses; grace and truth were realized through Jesus Christ." (John 1:17) These are our choices and we can only choose one: Moses or Christ, Law or grace and truth. For me, I choose the latter!